SEO & Analytics

I have just started working for a company and need to add SEO keywords and Google Analytics to their site. Problem? I’m an HTML girl and their site was designed with WordPress 4.0.9. I’ve been reading all day and cannot find the direction to approach these additions from. Do I need to install WordPress locally and edit through it and its plugins? Or just edit the PHP files with and editor such as BlueFish or something similar? I am not looking for detailed support – just generalized direction so I can continue researching on how to add these two items to their existing site. Thanks for putting up with a “newbie.”